Generally, a rotating electrical machine such as a turbine generator is configured to seal hydrogen gas and the like within the device, and to cool respective sections such as a rotor, a stator iron core, and a stator coil by using the same as a coolant.
Further, a stator frame of the rotating electrical machine is provided with a high pressure bushing that penetrates the stator frame. The stator coil of the rotating electrical machine is wire bound to the high pressure bushing via a connecting conductor, and an electric output can be taken out from the rotating electrical machine through a hollow connecting conductor provided in the high pressure bushing. Since the high pressure bushing generates heat by a large current flowing in the hollow connecting conductor, the cooling gas introduced from inside the device is used for cooling.
Generally, the high pressure bushing structurally uses only an inner circumferential surface side of the hollow connecting conductor as a cooling surface. An outer circumferential surface side of the hollow connecting conductor ensures a space for maintaining an insulating distance, an insulating cylinder such as glass is also provided, and a sealing section that is vulnerable to heat is provided, however, an effect of cooling is not sufficiently enjoyed on the side thereof. In order to perform a sufficient cooling, a current value with which the current can be flown must be made small or the high pressure bushing must be made large by enlarging a conductor cross sectional area, neither of which is a crucial solution.
Under the circumstances, it is desired to provide a high pressure bushing and a rotating electrical machine, capable of improving cooling efficiency.